Ruby: Reform RBS signatures of lex_file and parse_file

[elizamarcum]

• This fixes RBS: Error using tapioca gem on herb because of malformed RBS on lex_file and parse_file #1989 by refining the approach taken in RBS: Update signatures of lex_file and parse_file #1990
  • I think that this resolves the feedback you posted in RBS: Update signatures of lex_file and parse_file #1990, but I'm happy to tweak this if it isn't quite what you were hoping for :)
• I also added two dependency lines to the Brewfile that were necessary for developing against this codebase
  • I'm happy to refine and/or swap those into their own PR, if you wish!

[marcoroth]

Awesome, thank you so much @elizamarcum, this is exactly the right approach in my option. A few things:

1. I think we also need to match the signatures for parse and lex in sig/herb_c_extension.rbs (or maybe it already perfectly matches?).
2. In order to get the RBS signarures in sig/* re-generated you need to run bundle exec rake rbs_inline, so that it looks at all the RBS inline comments in the Ruby files and writes the matching *.rbs file for it.
3. Great catch about the Brewfile changes, I guess I never caught these, since I somehow already had a matching Python+Ruby version installed already, feel free to keep the changes in here. 🙌🏼

Thank you so much for the contribution! 🙏🏼